The circle with the lines that you see on the top of the machine, rotates and displays the note you are playing. When you play a C the lines in the middle circle will be standing still.. from the C it will go outward, displaying all notes on a keyboard in 12 steps. It works by making a LED blink in the frequency of the sound, and rotating the image at a set speed. For the distance between the lines i used this table, it displays musical frequencys in centimeters. The sound part of the machine is based on logic ICs, but it also has a simple noise generator, and a filter. The sound the synth generates, is a 4 bit saw, or the same saw clipped to a square. The 4 bit saw is made with a binary counter and a resistor ladder. A nice feature is that you can mix in the binary pins, making one octave jumping chords (like c1 + c2 + c3 or d1 + d2 + d3 and so on).